U.S. patent application number 10/917936 was filed with the patent office on 2005-01-20 for flowmeter for the precision measurement of an ultra-pure material flow.
This patent application is currently assigned to Emerson Electric Co.. Invention is credited to Bell, Mark James, McNulty, Daniel Patrick, Pawlas, Gary Edward, Schlosser, Martin Andrew, Wheeler, Matthew Glen.
Application Number | 20050011287 10/917936 |
Document ID | / |
Family ID | 25540466 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050011287 |
Kind Code |
A1 |
Schlosser, Martin Andrew ;
et al. |
January 20, 2005 |
Flowmeter for the precision measurement of an ultra-pure material
flow
Abstract
A Coriolis flowmeter for the measurement of a process material
requiring an ultra high level of purity. This is achieved by
forming the entire Coriolis flowmeter of a PFA plastic material
that does not transfer ions from the Coriolis flowmeter to the
process material flowing through the flowmeter.
Inventors: |
Schlosser, Martin Andrew;
(Boulder, CO) ; Bell, Mark James; (Arvada, CO)
; Wheeler, Matthew Glen; (Arvada, CO) ; McNulty,
Daniel Patrick; (Westminster, CO) ; Pawlas, Gary
Edward; (Louisville, CO) |
Correspondence
Address: |
DUFT SETTER OLLILA & BORNSEN LLC
2060 BROADWAY
SUITE 300
BOULDER
CO
80302
US
|
Assignee: |
Emerson Electric Co.
St. Louis
MO
|
Family ID: |
25540466 |
Appl. No.: |
10/917936 |
Filed: |
August 13, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10917936 |
Aug 13, 2004 |
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09994251 |
Nov 26, 2001 |
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6776053 |
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Current U.S.
Class: |
73/861.354 |
Current CPC
Class: |
G01F 1/8427 20130101;
G01F 1/8495 20130101; G01F 1/8409 20130101; G01F 1/8418 20130101;
G01F 1/8472 20130101; G01F 1/849 20130101; G01F 15/006 20130101;
G01F 1/8477 20130101; G01F 1/8404 20130101; G01F 1/8413
20130101 |
Class at
Publication: |
073/861.354 |
International
Class: |
G01F 001/58 |
Claims
What is claimed:
1. A Coriolis flowmeter for measuring a process material flow
having an ultra high level of purity, said Coriolis flowmeter
comprising: a base; flow tube apparatus adapted to receive said
process material flow, said flow tube apparatus is formed of a
material, such as PFA, that does not transfer ions from said flow
tube apparatus to said process material; end portions of said flow
tube apparatus coupled to said base to create substantially
stationary nodes at said end portions; a driver coupled to said
flow tube apparatus for vibrating said flow tube apparatus
containing said process material flow; pickoff means coupled
signalwise to said flow tube apparatus for generating signals
representing induced Coriolis deflections of said vibrating process
material filled flow tube apparatus; and meter electronics that
receives said signals from said pickoff means and generates output
information pertaining to said process material flow.
2. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus defines a substantially straight single flow
tube.
3. The Coriolis flowmeter of claim 1 characterized in that the
entirety of the wetted flow path of said Coriolis flowmeter
comprises a PFA substance.
4. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus defines more than one flow tube.
5. The Coriolis flowmeter of claim 1 characterized in that said
pickoff means is an electromagnetic device having a magnet
connected to said flow tube apparatus and further having a
coil.
6. The Coriolis flowmeter of claim 1 characterized in that said
pickoff apparatus comprises a light source that emits a beam and an
optical detector that receives said beam, said beam is oriented
substantially transverse to said flow tube; said light source and
said optical detector are spaced apart from said flow tube on
opposite sides of said flow tube apparatus; said flow tube
apparatus is positioned between said light source and said optical
detector to alter the characteristics of a light beam received by
said optical detector from said light source, said optical detector
is responsive to said alteration to generate said signals
representing said Coriolis deflections.
7. The Coriolis flowmeter of claim 1 characterized in that said
base has a lower surface and an inner pair of upwardly extending
walls as well as an outer pair of upwardly extending walls parallel
to said inner walls; openings in each of said upwardly extending
walls are coaxially aligned to receive said flow tube
apparatus.
8. The Coriolis flowmeter of claim 1 characterized in that said
base is substantially unshaped and has a lower surface and a pair
of upwardly extending walls proximate sides of said base; openings
in each of said upwardly extending walls are coaxially aligned to
receive said flow tube apparatus.
9. The Coriolis flowmeter of claim 1 characterized in that said
base is a solid rectangular element defining a parallelepiped; said
flow tube apparatus is connected to posts affixed to said base
between upwardly extending walls affixed to a top surface of said
base.
10. The Coriolis flowmeter of claim 2 characterized in that said
flow tube apparatus comprises said single flow tube and that said
base has a mass substantially greater than the mass of said flow
tube with process material.
11. A Coriolis flowmeter for measuring a flow of process material
having an ultra high level of purity; said Coriolis flowmeter
comprising: a single flow tube formed of a material, such as PFA,
that does not transfer ions from said single flow tube to said
process material; said single flow tube has high flexibility and
further has a stiffness substantially lower than a metal or glass
flow tube; the entirety of the wetted path of said Coriolis
flowmeter comprises said PFA material; a driver coupled to said
single flow tube for vibrating said single flow tube containing
said process material; a massive base coupled by upwardly extending
walls to ends of said single flow tube to absorb undesired
vibratory forces generated by said vibrating flow tube; said base
defines stationary nodes proximate opposing ends of said flow tube;
an inlet connector connected to said massive base and adapted to
receive a flow of said process material from a supply tube; an
inlet end of said single flow tube is affixed to said inlet
connector; said input connector sealably connects said inlet end of
said single flow tube to an outlet end of said supply tube to
effect the extension of said process material flow in said supply
tube to said single flow tube; said inlet connector maintains said
inlet end of said flow tube fixed with respect to said massive
base; an outlet end of said single flow tube affixed to a second
connector for extending said process material flow via an exit tube
towards a user destination; a pair of pickoffs coupled to said
single flow tube on opposite axial sides of said driver for
generating signals representing Coriolis induced deflections of
said vibrating material filled single flow tube; meter electronics;
and conductors extending signals from said pickoffs to said meter
electronics; said meter electronics receives said pickoff output
signals and generates output information pertaining to said process
material flow.
12. The Coriolis flowmeter of claim 11 further comprising; a return
tube connected to said massive base parallel to said single flow
tube; end portions of said single flow tube and said return tube
are glued to said massive base to maintain said single flow tube
and said return tube immovable with respect to said massive base;
an inlet of said return tube; an intermediate tube connecting said
outlet end of said single flow tube and said inlet end of said
return tube via said second connector to extend said process
material flow from said outlet end of said single flow tube to said
inlet of said return tube; an outlet connector connected to said
massive base for receiving said flow of said process material from
said outlet end of said return tube; said outlet connector sealably
connects said outlet end of said return tube to an inlet end of an
exit tube to effect the extension of said process material flow in
said return tube to said exit tube; said exit tube is adapted to
extend said process material flow to a user destination.
13. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus has high flexibility and a stiffness
substantially lower than flow tube apparatus formed of metal or
glass.
14. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus has walls substantially thinner than the
diameter of the inner portion of the flow tube apparatus through
which said material flows.
15. The Coriolis flowmeter of claim 11 characterized in that said
single flow tube is substantially straight.
16. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus comprises a single flow tube and that said base
is substantially U-shaped and has a mass substantially greater than
the mass of said flow tube with process material.
17. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus has: a drive frequency deflection that extends
over the entirety of the axial length of the active portion of said
flow tube apparatus; and further has a Coriolis deflection that
extends over the entirety of the axial length of the active portion
of said flow tube apparatus.
18. The Coriolis flowmeter of claim 1 characterized in that said
base is massive and said flow tube apparatus comprises a single
flow tube connected to said massive base to define a dynamically
balanced structure when vibrated with material flow by said
driver.
19. The Coriolis flowmeter of claim 1 characterized in that: said
flow tube apparatus comprises a single flow tube defining a
dynamically unbalanced structure; and said base has a mass
sufficiency large to vibrationally communicate with said flow tube
so that said Coriolis flowmeter defines a dynamically balanced
structure when in use.
20. The Coriolis flowmeter of claim 1 characterized in that said
flow tube apparatus comprises at least one flow tube having a
substantially constant outer diameter.
Description
RELATED APPLICATIONS
[0001] This patent application is a continuation of pending
application Ser. No. 09/994,251, filed Nov. 26, 2001, and entitled
Flowmeter for the Precision Measurement of an Ultra-Pure Material
Flow, and is hereby incorporated by reference into this application
to the extent as fully set forth herein. This application is
further related to the following concurrently filed patent
applications assigned to the same assignee:
[0002] 1. U.S. application Ser. No. 09/994,257, filed Nov. 26,
2001, titled METHOD OF MANUFACTURING A FLOWMETER FOR THE PRECISION
MEASUREMENT OF AN ULTRA-PURE MATERIAL FLOW;
[0003] 2. U.S. application Ser. No. 09/994,264, filed Nov. 26,
2001, titled MANUFACTURING FLOW METERS HAVING A FLOW TUBE MADE OF A
FLUOROPOLYMER SUBSTANCE; and
[0004] 3. U.S. application Ser. No. 09/995,174, filed Nov. 26,
2001, titled HIGH PURITY CORIOLIS MASS FLOW CONTROLLER, now Patent
No. 6,606,917.
FIELD OF THE INVENTION
[0005] This invention relates to a Coriolis flowmeter that measures
a flow of process material having an ultra high level of
purity.
Problem
[0006] It is known to use Coriolis effect mass flowmeters to
measure mass flow and other information pertaining to materials
flowing through a pipeline as disclosed in U.S. Pat. No. 4,491,025
issued to J. E. Smith, et al. of Jan. 1, 1985 and Re. 31,450 to J.
E. Smith of Feb. 11, 1982. Flowmeters have one or more flow tubes
of a straight, curved or irregular configuration. Each flow tube
has a set of natural vibration modes which may be of a simple
bending, torsional, or twisting type. Each material filled flow
tube is driven to oscillate at resonance in one of these natural
modes. The natural vibration modes are defined in part by the
combined mass of the flow tubes and the material within the flow
tubes. If desired, a flowmeter need not be driven at a natural
mode.
[0007] Material flows into the flowmeter from a connected material
source on the inlet side. The material passes through the flow tube
or flow tubes and exits the outlet side of the flowmeter.
[0008] A driver applies force to oscillate the flow tube. When
there is no material flow, all points along a flow tube oscillate
with an identical phase in the first bending mode of the flow tube.
Coriolis accelerations cause each point on the flow tube to have a
different phase with respect to other points on the flow tube. The
phase on the inlet side of the flow tube lags the driver; the phase
on the outlet side leads the driver. Pickoffs are placed on the
flow tube to produce sinusoidal signals representative of the
motion of the flow-tube. The phase difference between two sensor
signals is divided by the frequency of oscillation to obtain a
delay which is o proportional to the mass flow rate of the material
flow.
[0009] It is known to use flowmeters having different flow tube
configurations. Among these configurations are single tube, dual
tube, straight tube, curved tube, and flow tubes of irregular
configuration. Most of the flowmeters are made of metal such as
aluminum, steel, stainless steel and titanium. Glass flow tubes are
also known.
[0010] The positive attributes of titanium in flowmeters are its
high strength and low coefficient of thermal expansion (CTE). The
negative attributes of titanium are its metallic properties and
cost of manufacturing. In semiconductor wafer processing, metal
ions are a contaminant. Metal ions in contact with the wafer areas
of an integrated circuit can cause a short circuit and ruin the
device. Also, a Titanium flowmeter is difficult and expensive to
produce.
[0011] The prior art also suggests plastic flow tubes and plastic
flowmeters. This includes prior art in which the entirety of the
flowmeter is plastic as well as that in which only the flow tube is
formed of plastic. Much of this prior art merely contains an
assertion that a flowmeter may be made of various materials such as
steel, stainless steel, titanium or plastic. This prior art is not
instructive in so far as concerns the disclosure of a plastic
Coriolis flowmeter that can accurately output information over a
range in operating conditions including temperature.
[0012] The mere substitution of a plastic flow tube for a metal
flow tube will produce a structure that looks like a flowmeter.
However, the structure will not function as a flowmeter to generate
accurate output information over a useful range of operating
conditions. The mere assertion that a flowmeter could be made out
of plastic is nothing more than the abstraction that plastic can be
substituted for metal. It does not teach how a plastic flowmeter
can be manufactured to generate accurate information over a useful
range of operating conditions.
[0013] It is a problem in some applications that the typical
Coriolis flowmeter may contaminate the process material. This is
undesirable for systems in which material of an ultra high level of
purity must be delivered by the flowmeter to a user application.
This is the case in the fabrication of semi-conductor wafers which
requires the use of a process material that is free of contaminants
including ions migrating from the tubes of the process material
flow path. In such applications, the flow tube can be a source of
contaminants. The metal walls of a flow tube can release ions into
the process material flow. The released ions can cause the chips on
a semi-conductor wafer to be defective. The same is true for a
glass flow tube which can release the lead ions from the glass into
the process material flow. The same is also true for the flow tubes
formed of conventional plastics.
[0014] A plastic termed PFA is free from this objection since the
material of which it is composed does not release deleterious ions
into the material flow. The use of PFA for a flow tube is suggested
in U.S. Pat. No. 5,918,285 to Vanderpol. This suggestion is
incidental to the Vanderpol disclosure since the patent discloses
no information regarding how a flowmeter having a PFA flow tube
could be manufactured to generate accurate flow information.
[0015] Flow tubes lined with PFA, as disclosed in U.S. Pat. No.
5,403,533 to Dieter Meier, attempted to combine the positive
attributes of both metal and plastic technologies but encountered
new challenges that could not be solved until the present
invention. Metal flow tubes lined with PFA allow metal ions to
migrate through the thin PFA coating layer and into the flow stream
to cause contamination. Also, the metal flow tube material and the
PFA liner have different thermal properties. This caused the PFA
liner to disengage from the flow tube to create leaks and
performance problems. The manufacturing process for lining the
metal flow tubes with PFA is also extremely costly.
Solution
[0016] The above and other problems are solved and an advance of
the art is achieved by the present invention which discloses a
Coriolis flowmeter having at least one flow tube formed of
perfluoroalkoxy copolymer (PFA) plastic. The flow tube is coupled
to a driver and to at least one pickoff sensor to enable the PFA
flow tube to function as part of Coriolis flowmeter that can
provide accurate output information over range of operating
conditions for a process material flow of ultra high purity
suitable for use in applications such as semi-conductor fabrication
and the like which require the material flow to be free of
contaminants down to the ionic level.
[0017] A flow path constructed entirely of PFA has many of the
benefits of Titanium and PFA lined flow tubes without the
drawbacks. PFA is a fluoropolymer with superior chemical
resistance, little metal ion release, low particle generation, and
is manufacturable without expending large amounts of capital. PFA
material is strong and can be extruded into high quality thin wall
tubing. Thin-walled PFA tubing has low flexural stiffness enabling
a higher sensitivity to mass flow rate and improved immunity to
elastic dynamic interaction between the flow tube and the process
pipeline. The material and physical properties of PFA allow larger
tube vibration amplitudes at lower stress levels and result in near
infinite fatigue life span. Also, the higher vibration amplitude
allows the use of small low-mass transducers, which in turn
improves density sensitivity and immunity to mount variation.
[0018] A first preferred exemplary embodiment of the invention
comprises a flowmeter having a single PFA plastic flow tube coupled
to a massive metal base which balances the end node vibration of
the flow tube. The base is U-shaped and the plastic flow tube
extends through coaxial holes in the two legs of the U. The plastic
flow tube is affixed to the holes in the base by means of an
appropriate adhesive such as cyanoacrylate also termed Loctite 420.
The longitudinal center of the flow tube is affixed to an
electromagnetic driver which receives a drive signal from a meter
electronics to vibrate the flow tube transversely to the
longitudinal axis of the flow tube. This vibration may be at the
first bending resonant frequency of the flow tube. The flow tube is
coupled to pickoffs which detect the Coriolis response of the
vibrating flow tube with material flow. In the first embodiment,
the pickoffs may be a conventional electromagnet combination with
magnets affixed to the flow tube and a coil affixed to the base. In
an alternative embodiment, the pickoffs are optical devices which
generate a light beam and that is modulated by the vibrations of
the flow tube. The optical sensing embodiment offers the advantage
that the weight of the pickoff magnets is removed from the
vibrating flow tube. This increases density sensitivity. The driver
is a source of heat that can raise the temperature of the plastic;
thermally expand the plastic and degrade the accuracy of the
generated output information. In this embodiment, the driver is
advantageously affixed on top of the flow tube when in use. This
mounting arrangement has the advantage that the heat generated by
the driver radiates upwardly away from the flow tube.
[0019] In accordance with another embodiment, the magnets
associated with the driver and sensor pickoffs have low mass since
they are small and do not have keepers or pole pieces. The magnets
and coils have been optimized to make the magnets as small (low
mass) as possible. The magnet material has been chosen to have the
most magnetic field per unit mass as possible. The tube geometry
has been designed to achieve the desired motion with as little
drive force as possible. PFA has naturally low damping, so drive
force is inherently low due to selecting this material for the flow
tube. All of these factors contribute to achieving low mass
transducer parts on the flow tube. This is advantageous since it
reduces the physical loading of the flow tube and enhances the
output accuracy of the flowmeter.
[0020] The single flow tube comprises an unbalanced structure whose
vibration is minimized by the massive base. The ratio of the mass
of the base to mass of the single plastic flow tube together with
its magnetic material mass is in the order of 3,000 to 1. This
results in a heavy base structure having a weight of approximately
13 pounds for a flow tube, plus magnets and material mass having a
total weight of about 2 grams. Although the 13 pound weight
minimizes the vibrations at the nodes of the flow tube, it has a
disadvantage of increasing the weight of the equipment of which the
flowmeter is a part. These vibrations may be minimized by the use
of a dynamic balancer or a active dynamic balancer. The active
dynamic balancer transmits signals to the meter electronics which
analyzes the signals and returns a control signal to the active
dynamic balancer to reduce the undesired vibrations. This has the
advantage that the overall weight of the base structure may be
reduced from 13 pounds down to about 2 pounds.
[0021] As mentioned, the first preferred embodiment comprises a
Coriolis flowmeter having a single straight tube operating in an
unbalanced mode in cooperation with a massive base. Other flow tube
configurations are provided by other embodiments of the invention.
The invention may be practiced with the use of dual flow tubes
vibrating in phase opposition. These dual tubes may either be
straight, they may be unshaped, or they may be of a irregular
configuration. The use of dual flow tubes is advantageous in that
it provides a dynamically balanced structure that reduces the mass
of the base required to mount the flow tubes.
[0022] An additional embodiment that can be associated with any
tube configuration is the provision of a temperature measurement
device. A preferred embodiment is the use of a Resistive
Temperature Device (RTD) attached to a flow tube. If desired, the
temperature can be measured using an infrared temperature
measurement device. The benefits to this device is that it is
non-contact and can be located off the tube, thereby reducing mass
on the tube. Also, the RTD can be mounted to another flow carrying
tube in the sensor which is not the vibrating flow tube.
[0023] Another embodiment comprises a massive base having upwardly
extending sidewalls and a single flow tube extending through
coaxial holes in the sidewalls. The base has an inner and an outer
pair of upwardly extending walls. The inner walls contain the
stationary vibrational nodes of the active portion of the flow
tube; the outer walls mount connectors to which an inlet of the
flow tube is connected at one end and an outlet of the flow tube is
connected at the other end. This arrangement provides a dynamically
unbalanced structure comprising a single flow tube with any
vibrations at the nodes of the active portion of the flow tube
being suppressed by the inner pair of upwardly extending walls.
[0024] Still another embodiment of the invention comprises a
massive base having upwardly extending side walls and a pair of
flow tubes extending through holes in the side walls. The two flow
tubes are connected in series in so far as concerns the process
material flow. This connection is accomplished by means of short
u-shaped length of PFA tubing at one end of the base. This short
unshaped length of tubing connects an outlet end of the first flow
tube to an inlet end of the second flow tube which is positioned in
the base parallel to the first flow tube. With this arrangement, an
inlet end of the first flow tube and an outlet end of the second
flow tube are positioned in the same upwardly extending wall of the
massive base. The two flow tubes are vibrated by separate drivers
in phase opposition. Each flow tube also has its pair of pickoffs
for detecting the Coriolis response of its flow tube with material
flow.
[0025] In summary, the Coriolis flowmeter embodying the present
invention is advantageous in that it provides for the measurement
and delivery of a process material having an ultra high level of
purity. This level of purity is provided by the use of a PFA
plastic flow tube which is superior to metals, glass and ordinary
plastics all of which permit ion transfer from the flow tube
material to the processed material. The processed material may
typically comprise a slurry which is an organic compound used as a
polishing agent in the fabrication of wafers in the semi-conductor
industry. This polishing operation provides a flat surface for the
wafers. The polishing operation can take about an hour during which
time the slurry must be free from any contaminants. The deposit of
a single undesired ion onto a semi-conductor wafer can short
circuit all or a portion of the wafer and render it useless.
[0026] An aspect of the invention is a Coriolis flowmeter for
measuring a process material flow having an ultra high level of
purity, said Coriolis flowmeter comprising:
[0027] a base;
[0028] flow tube apparatus adapted to receive said process material
flow, said flow tube apparatus is formed of a material that does
not transfer ions from said flow tube apparatus to said process
material;
[0029] end portions of said flow tube apparatus are coupled to said
base to create substantially stationary nodes at said end
portions;
[0030] said flow tube apparatus has high flexibility and also has a
stiffness substantially lower than flow tube apparatus formed of
metal or glass;
[0031] a driver coupled to said flow tube apparatus for vibrating
said flow tube apparatus containing said process material flow;
[0032] pickoff means coupled signalwise to said flow tube apparatus
for generating signals representing induced Coriolis deflections of
said vibrating process material filled flow tube apparatus; and
[0033] meter electronics that receives said signals from said
pickoff means and generates output information pertaining to said
process material flow.
[0034] Preferably said flow tube apparatus defines a substantially
straight single flow tube.
[0035] Preferably the entirety of the wetted flow path of said
Coriolis flowmeter comprises a PFA substance.
[0036] Preferably said flow tube apparatus defines more than one
flow tube.
[0037] Preferably said pickoff means is an electro-magnetic device
having a magnet connected to said flow tube apparatus and further
having a coil.
[0038] Preferably said pickoff means comprises a light source and
an optical detector;
[0039] said vibrating flow tube apparatus is positioned between
said light source and said optical detector to alter the
characteristics of the light received by said optical detector from
said light source;
[0040] said optical detector is responsive to said alteration to
generate said signals representing said Coriolis deflections.
[0041] Preferably said base has a lower surface and an inner pair
of upwardly extending side walls as well as an outer pair of
upwardly ending walls;
[0042] openings in each of said upwardly extending walls are
coaxially aligned to receive said flow tube apparatus.
[0043] Preferably said base is substantially u-shaped and has a
lower surface and a pair of upwardly extending walls proximate
sides of said base; openings in each of said upwardly extending
walls are coaxially aligned to receive said flow tube
apparatus.
[0044] Preferably ends of said flow tube apparatus extend beyond
said walls.
[0045] Preferably said base is a solid rectangular element defining
a parallelepiped;
[0046] said flow tube apparatus is connected to posts affixed
between said walls to a top surface of said base.
[0047] Preferably an inlet of said flow tube apparatus receives
said process material flow from a supply tube;
[0048] an outlet of said flow tube apparatus is coupled to an inlet
of a return tube;
[0049] said return tube is coupled to said base and is positioned
parallel to said flow tube apparatus and extends through walls of
said base, and
[0050] said return tube is adapted to be connected to an exit tube
to extend said process material flow towards a user
application.
[0051] Preferably said flow tube apparatus comprises a single flow
tube and that said base has a mass substantially greater than the
mass of said flow tube with process material.
[0052] Preferably the mass of said base is at least 1000 times the
mass of said single flow tube with process material.
[0053] Preferably the mass of said base is at least 100 times the
mass of said single flow tube with process material.
[0054] Preferably said driver is affixed to the top of said single
flow tube when in use.
[0055] Preferably a dynamic balancer means coupled to said base
proximate said nodes to maintain said nodes at a reduced level of
vibration.
[0056] Preferably said dynamic balancer means is an active dynamic
balancer controlled by the exchange of signals with said meter
electronics.
[0057] Preferably said base is substantially unshaped and has a
lower surface and a pair of upwardly extending side walls
containing coaxially aligned openings for receiving said single
flow tube.
[0058] Preferably said single flow tube extends through coaxial
openings in said walls.
[0059] Preferably said flow tube apparatus comprises a first and a
second flow tube coupled to said base and positioned parallel to
each other, said first and second flow tubes are adapted to be
vibrated in phase opposition by said driver.
[0060] Preferably said driver is affixed to both said first flow
tube and said second flow tube and is adapted to vibrate said first
and second flow tubes in phase opposition;
[0061] said pickoffs being affixed to both said first and second
flow tubes to detect the Coriolis deflections of said first and
second flow tubes.
[0062] Preferably said first and second flow tubes are connected in
series with respect to said material flow.
[0063] Preferably said first and second flow tubes are connected in
parallel with respect to said material flow.
[0064] Preferably a return tube coupled to said base and oriented
parallel to said first and second flow tubes;
[0065] said return tube receives said process material flow from
said first and second flow tubes and extends said material flow
towards a user application.
[0066] Preferably said base is unshaped and has upwardly extending
walls;
[0067] said first and second flow tubes extend through said walls
of said base and have inlet and outlet ends projecting beyond the
outer surfaces of said walls.
[0068] Another aspect comprises a Coriolis flowmeter for measuring
a flow of process material having an ultra high level of
purity;
[0069] said Coriolis flowmeter comprising:
[0070] a single flow tube formed of a material, such as PFA, that
does not transfer ions from said single flow tube to said process
material;
[0071] said single flow tube has high flexibility and further has a
stiffness substantially lower than a metal or glass flow tube;
[0072] the entirety of the wetted path of said Coriolis flowmeter
comprises said PFA material;
[0073] a driver affixed to said single flow tube for vibrating said
single flow tube containing said process material flow;
[0074] a massive base affixed to ends of said single flow tube to
absorb undesired vibratory forces generated by said vibrating flow
tube;
[0075] said base defines stationary nodes at ends of said flow
tube;
[0076] an inlet connector connected to said massive base and
adapted to receive a flow of said process material from a supply
tube;
[0077] an inlet end of said single flow tube is affixed to said
inlet connector;
[0078] said input connector sealably connects said inlet end of
said single flow tube to an outlet end of said supply tube to
effect the extension of said process material flow in said supply
tube to said single flow tube;
[0079] said inlet connector maintains said inlet end of said flow
tube fixed with respect to said massive base;
[0080] an outlet end of said single flow tube affixed to a second
connector for extending said process material flow via an exit tube
towards a user destination;
[0081] a pair of pickoffs coupled to said single flow tube on
opposite sides of said driver for generating signals representing
Coriolis induced deflections of said vibrating material filled
single flow tube;
[0082] meter electronics; and
[0083] conductors extending signals from said pickoffs to said
meter electronics;
[0084] said meter electronics receives said pickoff output signals
and generates output information pertaining to said process
material flow.
[0085] Preferably a return tube connected to said massive base
parallel to said single flow tube;
[0086] end portions of said single flow tube and said return tube
are glued to said massive base to maintain said single flow tube
and said return tube immovable with respect to said massive
base;
[0087] an inlet of said return tube;
[0088] an intermediate tube connecting said outlet end of said
single flow tube and said inlet end of said return tube via said
second connector to extend said process material flow from said
outlet end of said single flow tube to said return tube;
[0089] an outlet connector connected to said massive base for
receiving said flow of said process material from said outlet end
of said return tube;
[0090] said outlet connector sealably connects said outlet end of
said return tube to an inlet end of an exit tube to effect the
extension of said process material flow in said return tube to said
exit tube;
[0091] said exit tube is adapted to extend said process material
flow to a user destination.
[0092] Preferably said pickoffs are electromagnetic devices each
having a magnet and a coil.
[0093] Preferably said pickoffs each comprises a light source and
an optical detector with the magnitude of the Coriolis deflection
of said single flow tube defining the magnitude of the output
current of said optical detector.
[0094] Preferably said massive base has a pair of upwardly
extending parallel side walls having coaxial openings through which
said single flow tube and said return tube extend.
[0095] Preferably said massive base is substantially unshaped.
[0096] Preferably said massive base is a solid rectangular element
defining a parallelepiped;
[0097] said single flow tube is mounted to upwardly extending posts
affixed to a surface of said massive base.
[0098] Preferably ends of said single flow tube and said return
tube extend beyond the outer surface of each leg.
[0099] Preferably said single flow tube is substantially
straight.
[0100] Preferably Coriolis flowmeter comprises a second flow tube
coupled to said massive base to define a dynamically balanced
structure when vibrated by said driver while containing said
process material.
[0101] Preferably said driver is positioned when in use on a top
surface of said single flow tube.
[0102] Preferably a dynamic balancer means coupled to said massive
base proximate said nodes to reduce the vibration of said
nodes.
[0103] Preferably said dynamic balancer means is an active dynamic
balancer controlled by the exchange of signals with said meter
electronics.
[0104] Preferably said first and second flow tubes have an
irregular shape.
[0105] Preferably the mass of said massive base is at least 100
times the mass of said flow tube with material flow.
[0106] Preferably the mass of said massive base is at least 1000
times the mass of said single flow tube with material flow.
[0107] Preferably said driver vibrates said flow tube at a resonant
frequency of said material filled flow tube.
[0108] Preferably said driver vibrates said flow tube at a non
resonant frequency of said material filled flow tube.
[0109] Preferably said Coriolis flowmeter is adapted to extend a
flow of corrosive material including nitric acid.
DESCRIPTION OF THE DRAWINGS
[0110] These and other advantages and features of the present
invention may be better understood in connection with a reading of
the following detailed description thereof in connection of the
drawings in which:
[0111] FIG. 1 discloses a perspective view of a first exemplary
embodiment of the invention.
[0112] FIG. 2 is a top view of the embodiment of FIG. 1.
[0113] FIG. 3 is a front view of the embodiment of FIG. 1.
[0114] FIG. 4 is a cross-sectional view taken along lines 4-4 of
FIG. 2.
[0115] FIG. 5 is a perspective view of an alternative embodiment
having a pair of base elements.
[0116] FIG. 6 discloses a dynamically balanced flowmeter having a
U-shaped base.
[0117] FIGS. 7 and 8 disclose a flowmeter having optical
pickoffs.
[0118] FIGS. 9 and 10 disclose flowmeters having dynamic
balancers.
[0119] FIG. 11 discloses a flowmeter having a pair of substantially
U-shaped flow tubes.
[0120] FIGS. 12 and 13 discloses another embodiment of a flowmeter
having a pair of dynamically balanced straight flow tubes.
[0121] FIG. 14 discloses an alternative embodiment having a single
flow tube and no return tube.
[0122] FIG. 15 discloses an alternative embodiment having two flow
tubes vibrated in phase opposition.
[0123] FIG. 16 discloses an alternative embodiment having a single
flow tube.
DETAILED DESCRIPTION
[0124] Description of FIG. 1
[0125] FIG. 1 is a perspective view of a first possible exemplary
embodiment of the invention and discloses a flowmeter 100 having a
flow tube 102 inserted through legs 117, 118 of base 101. Flowmeter
200 has a base 101, sidewalls 119 and 120, a front surface 116 and
top wall surfaces 117 and 118. Pickoffs LP0 and RP0 and driver D
are coupled to flow tube 102. Flowmeter 100 receives a process
material flow from supply tube 104 and extends the flow through
connector 108 to flow tube 102. Flow tube 102 is vibrated at its
resonant frequency with material flow by driver D. The resulting
Coriolis deflections are detected by pickoffs LP0 and RP0 which
apply signals over conductors 112 and 114 to meter electronics 121.
Meter electronics 121 receives the pickoff signals, determines the
phase difference between them, determines the frequency of
oscillation and applies output information pertaining to the
material flow over output path 122 to a utilization circuit not
shown. The material flow passes from flow tube 102 and through tube
106 which redirects the material flow through return tube 103
through connector 107 to exit tube 105 which delivers the material
flow to a user application. This user application may be a
semiconductor processing facility. The process material may be a
semiconductor slurry which is applied to the surface of a
semiconductor wafer to form a flat surface. The PFA material used
in the flow tubes shown on FIG. 1 ensures that the process material
is free of impurities such as ions which could be transferred from
the walls of metals or glass flow tubes. Locking holes 130 receive
set screws 411 to fixably connect element 111 to base 101 as shown
on FIG. 4.
[0126] In use, flow tube 102 is of a narrow diameter approximating
one half that of a soda straw, but with thicker walls and of
negligible weight such as, for example, 0.8 gram plus 0.5 gram for
the process material. This excludes the weight of the magnets. The
magnets associated with the pickoffs and driver have a mass of 0.2
gram each so that the combined mass of the flow tube 102, the
affixed magnets and the process material is approximately 2 grams.
Vibrating flow tube 102 is a dynamically unbalanced structure. Base
102 is massive and weighs approximately 12 pounds. This provides a
ratio of the mass of the base to that of a material filled flow
tube of approximately 3000. A base of this mass is sufficient to
absorb vibrations generated by the dynamically unbalanced flow tube
102 with material flow.
[0127] Connectors 107, 108, 109 and 110 connect tubes 104, 105 and
intermediate tube 106 to the ends of flow tube 102 and return tube
103. These connectors are shown in detail in FIG. 4. The connectors
have a fixed portion 111 that includes threads 124. The movable
portion of connectors 107 through 110 are threaded onto male
threads 124 to connect their respective tubes to the fixed body of
the connector of which the fixed portion 111 is a part. These
connectors function in a manner similar to the well known copper
tubing flared connectors to connect tubes 104, 105 and 106 to ends
of flow tube 102 and return tube 103. Details regarding the
connectors are further shown in FIG. 4. RTD is a temperature sensor
that detects the temperature of return tube 103 and transmits
signals representing the detected temperature over path 125 to
meter electronics.
[0128] Description of FIG. 2
[0129] In FIG. 2 is a top view of flowmeter 100 of FIG. 1. Pickoffs
LP0 and RP0 and driver D each include a coil C. Each of these
elements further includes a magnet which is affixed to the bottom
portion of flow tube 102 as shown in FIG. 3. Each of these elements
further includes a base, such as 143 for driver D, as well as a
thin strip of material, such as 133 for driver D. The thin strip of
material may comprise a printed wiring board to which coil C and
its winding terminals are affixed. Pickoffs LP0 and RP0 also have a
corresponding base element and a thin strip fixed to the top of the
base element. This arrangement facilitates the mounting of a driver
or a pickoff to be accomplished by the steps of gluing a magnet M
to the underside of PFA flow tube, gluing the coil C to a printed
wiring board 133 (for driver D), positioning the opening in coil C
around the magnet M, moving the coil C upwardly so that the magnet
M fully enters the opening in coil C, then positioning base element
143 underneath the printed wiring board 133 and gluing or bolting
these elements together so that the bottom of base 143 is affixed
by glue to the surface of the massive base 101.
[0130] The male threads 124 of connectors 107-110 are shown on FIG.
2. The inner details of each of these elements is shown on FIG. 4.
Opening 132 receives conductors 112, 113 and 114. Meter electronics
121 of FIG. 1 is not shown on FIG. 2 to minimize drawing
complexity. However it is to be understood that the conductors 112,
113 and 114 extend through opening 126 and further extend over path
123 of FIG. 1 to meter electronics 121 of FIG. 1.
[0131] Description of FIG. 3
[0132] FIG. 3 shows pickoffs LP0, RP0 and driver D as comprising a
magnet M affixed to the bottom portion of flow tube 102 and a coil
C affixed to the base of each of elements LP0, RP0 and driver
D.
[0133] Description of FIG. 4
[0134] FIG. 4 is a sectional taken along line 4-4 of FIG. 2. FIG. 4
discloses all the elements of FIG. 3 and further details of
connectors 108 and 109. FIG. 4 further discloses openings 402, 403
and 404 in base 101. The top of each of these openings extends to
the lower surface of the base of pickoffs LP0, RP0 and driver D.
The coil C and magnet M associated with each of these elements is
also shown on FIG. 4. Meter electronics 121 of FIG. 1 is not shown
on FIGS. 3 and 4 to minimize drawing complexity. Element 405 in
connector 108 is the inlet of flow tube 102; element 406 in
connector 109 is the outlet of flow tube 102.
[0135] The fixed portion 111 of connector 108 includes male threads
409 which screw into mating threads in base 401 to attach fixed
connector portion 111 to segment 401 of base 101. The fixed body of
connector 109 on the right is similarly equipped and attached by
threads 409 to element 401 of base 101. Fixed portion 111 of
connector 108 further includes a threaded portion 124 whose threads
receive the movable portion 415 of connector 108. Connector 109 is
similarly equipped. Fixed portion 111 of connector 108 further
includes on its left a conical stub 413 which together with movable
element 415 acts as a flare fitting to force the right end of input
tube 104 over the conical stub 413 of fixed portion 111. This
creates a compression fitting that sealably affixes the flared
opening of supply tube 104 onto the conical stub portion 413 of
fixed portion 111 of the connector. The inlet of flow tube 102 is
positioned in connector fixed portion 111 and is flush with the
outer surface of stub 413. By this means, the process material
delivered by supply tube 104 is received by inlet 405 of flow tube
102. The process material flows to the right through flow tube 102
to fixed portion 111 of connector 109 where the outlet 406 of flow
tube 102 is flush with the end of connector stub 413. This sealably
affixes the outlet of tube 102 to connector 109. The other
connectors 107 and 110 of FIG. 1 are identical to those described
for the details of connectors 108 and 109 on FIG. 4.
[0136] Description of FIG. 5
[0137] FIG. 5 discloses flowmeter 500 as an alternative embodiment
of the invention similar to that of FIG. 1 except that the base of
the flowmeter 500 is not a single element and comprises separate
structures 517 and 518. Flow tube 502 and return tube 503 extend
through the elements 517, 518 to connectors 507 through 510 which
are comparable in every respect to connectors 107 through 110 of
FIG. 1. Flowmeter base elements 517, 518 are separate and each is
of sufficient mass to minimize the vibrations imparted by driver D
to the dynamically unbalanced structure comprising flow tube 502.
Base elements 517 and 518 rest on surface 515 of element 516 which
supports base elements 517 and 518.
[0138] All elements shown on FIG. 5 operate in the same manner as
do their corresponding elements on FIG. 1. This correspondence is
shown by the designation of each element which differs only in that
the first digit of the part designation of the element. Thus,
supply tube 104 on FIG. 1 corresponds to supply tube 504 on FIG.
5.
[0139] Description of FIG. 6
[0140] FIG. 6 discloses yet another alternative embodiment of the
invention as comprising flowmeter 600 which is different from the
embodiment of FIG. 1 in that flowmeter 600 has two active flow tube
602 and 603 which comprise a dynamically balanced structure that
does not require the massive base such as base 101 of FIG. 1. Base
601 may have significantly less mass than that of FIG. 1. Flowmeter
600 has connectors 607 through 610 comparable to connectors 107-110
of FIG. 1. In addition, it has connectors 611, 612. Process
material is received by flowmeter 600 from a supply tube 604. The
material extends via a connector 608 to the left end of flow tube
602. Flow tube 602 extends through leg 618 of base 601 and
connector 609 by means where it is connected to tube 615 which
loops back via connector 607 to flow tube 603. Flow tube 603 is
vibrated in phase opposition to flow tube 602 by driver D. The
Coriolis response of the vibrating flow tubes 602 and 603 is
detected by pickoffs LP0 and RP0 and transmitted via conductors not
shown to meter electronics element also not shown to minimize
drawing complexity.
[0141] The material flow through tube 603 proceeds to the right and
extends via connector 610 to tube 606 which loops back through
connector 611 and tube 616, connector 612 to return flow tube 605
which delivers the material flow to the application process of the
end user.
[0142] Flowmeter 600 is advantageous in that it comprises a
dynamically balanced structure of flow tubes 602 and 603 formed of
PFA material. The dynamically balanced structure is advantageous in
that the massive base 101 of FIG. 1 is not required. Base 601 may
be of conventional mass and vibrating PFA tubes 602 and 603 to
provide output information pertaining to the material flow. The PFA
flow tubes ensure that the material flow have an ultra high level
of purity.
[0143] Description of FIGS. 7 and 8
[0144] FIG. 7 discloses a top view of a flowmeter 700 comparable to
flowmeter 100 of FIG. 1. The difference between the two embodiments
is that flowmeter 700 uses an optical detector for pickoffs LP0 and
RP0. The details of the optical detectors are shown in FIG. 8 as
comprising a LED light source and photo-diode together with a flow
tube 702 interposed between the LED and photo-diode. At the rest
position of the flow tube, a nominal amount of light passes from
the LED to the photo-diode to generate a nominal output signal. A
downward movement of the flow tube increases the amount of light
received by the photo-diode; an upward movement of the flow tube
decreases the amount of light received by the photo-diode. The
amount of light received by the photo-diode translates to an output
current indicative of the magnitude of the Coriolis vibration for
the portion of the flow tube 702 associated with the LED and the
light source. The output of the photo-diodes are extended over
conductors 730 and 732 to meter electronics not shown in FIG. 7 to
minimize drawing complexity. The embodiment of FIG. 7 is otherwise
identical in every respect to the embodiment of FIG. 1 and includes
supply tubes 704, exit tube 705 together with connectors 707
through 710 flow tubes 702 and return tube 703. The parts of
flowmeter 700 and their counterparts on FIG. 1 and are designated
to facilitate the correspondence with the only difference being the
first digit of the designation of each element.
[0145] Description of FIG. 9
[0146] FIG. 9 discloses flowmeter 900 which corresponds to
flowmeter 100 of FIG. 1 except that flowmeter 900 is equipped with
dynamic balancers 932 and 933. Base 901 is smaller and of less mass
than 101 of FIG. 1. The dynamic balancers function to counteract
the vibrations imparted to legs 917 and 918 of base 901 by the
dynamically unbalanced structure comprising the material filled
vibrating flow tube 902. In the embodiment of FIG. 1, these
vibrations are absorbed by the massive base 101. In this
embodiment, the material filled flow tube with the attached magnets
weigh approximately 2 grams while the base weighs approximately 12
pounds. This limits the range of commercial applications for which
the flow tube of FIG. 1 since the upper limit on the size and mass
of the material filled vibrating flow tube 102 is limited by the
mass of the base that must be provided to absorb unbalanced
vibrations. Using the 3,000 to 1 ratio between the mass of the base
and the mass of the material filled vibrating flow tube, an
increase of one pound in the mass of the material filled flow tube
would require an increase of mass of 3,000 pounds for base 101.
This clearly limits the range of commercial applications in which
the flow tube 100 of FIG. 1.
[0147] Flowmeter 900 of FIG. 9 has a wider range of commercial
applications since the dynamic balancers 932 and 933 are affixed to
legs 917 and 918 to absorb much of the vibrations imparted to the
legs by the dynamically unbalanced vibrating flow tube 902. In
practice, dynamic balancers (DB) may be of any type including the
conventional mass and spring configuration as is well known in the
art of dynamic balancers.
[0148] Description of FIG. 10
[0149] FIG. 10 discloses a flowmeter 1000 that is identical to
flowmeter 900 except that the dynamic balancers of FIG. 10 are of
the active type (ADB) and are designated 1032 and 1033. These
active dynamic balancers are controlled by an exchange of signals
with meter electronics 1021 over paths 1023, 1024, 1025 and 1026.
Meter electronics 1021 receives signals over path 1003 from active
dynamic balancer 1032 representing the vibrations applied by the
dynamically unbalanced vibrating flow tube 1002 to leg 117. Meter
electronics receive these signals and generates a control signal
that is applied over path 1024 to active dynamic balancer 1032 to
counteract the flow tube vibrations. Operating in this manner,
active dynamic balancer 1032 can be controlled to reduce the
vibrations of leg 1017 to whatever magnitude may be desired so hat
the resulting mass of base 1001 may be of an acceptable level for
commercial use of flowmeter 1000. The active dynamic balancer 1033
mounted atop leg 1018 of base 1001 operates in the same manner as
described for the active dynamic balancer mounted to leg 1017.
[0150] Description of FIG. 11
[0151] FIG. 11 discloses yet another alternative embodiment
comprising a flowmeter 1100 having dual flow tubes 1101, 1102 which
are substantially U-Shaped and have right side legs 1103, 1104 and
left side legs 1105, 1106. The bottom portion of the side legs are
connected to form "Y" sections 1107 and 1108 which may be connected
to a suitable base not shown to minimize drawing complexity. The
dual flow tubes of flowmeter 1100 vibrate as dynamically balanced
elements around the axes W-W and W'-W' of brace bars 1009 and 1010.
Flow tubes 1101, 1102 are driven in phase opposition by driver D
affixed to the top portion of the U-shaped flow tubes. The Coriolis
deflections imparted by the vibrating material filled flow tubes
are detected by right pickoff RP0 and left pickoff LP0. Meter
electronics 1121 functions to apply signals over path 1123 to cause
driver D to vibrate flow tubes 1101, 1102 in phase opposition. The
Coriolis response detected by pickoffs LP0 and RP0 as transmitted
over paths 1122, 1124 to meter electronics 1121 which processes the
signals and derives material flow information which is transmitted
over output path 1124 to a utilizations circuit not shown.
[0152] Description of FIGS. 12 and 13
[0153] FIGS. 12 and 13 disclose a dynamically balanced flowmeter
1200 having a pair of flow tubes 1201 and 1202 which are vibrated
in phase opposition by driver D. The flow tubes receive a material
flow; driver D vibrates the flow tubes in phase opposition in
response to a drive signal received over path 1223 from meter
electronics 1221. The Coriolis response of the material filled
vibrating flow tubes is detected by pickoffs LP0 and RP0 with their
output being applied over conductors 1221 and 1224 to meter
electronics which processes the received signals to generate
material flow information that is applied over output path 1225 to
a utilization circuit not shown.
[0154] Description of FIG. 14
[0155] FIG. 14 discloses an alternative embodiment 1400 of the
invention comprising a massive base 1401 having an outer pair of
upwardly extending sidewalls 1443 and 1445 as well as an inner pair
of upwardly extending sidewalls 1417 and 1418. A single flow tube
1402 extends from an input connector 1408 on the left through the
four upwardly extending sidewalls to an output connector 1409 on
the right. The flow tube 1402 is vibrated by driver D with the
resulting Coriolis deflections of the vibrating flow tube with
material flow being detected by pickoffs LP0 and RP0 which transmit
signals over the indicated paths to meter electronics 1421 which
functions in the same manner as priorly described or FIG. 1.
Temperature sensing element RTD senses the temperature of the
material filled flow tube and transmits this information over path
1425 to meter electronics 1421.
[0156] The flowmeter of FIG. 14 differs from that of FIG. 1 in two
notable respects. The first is that the embodiment of FIG. 14 is
only a single flow tube 1402. The material flow extends through
this flow tube from input connector 1408; the output of the flow
tube is applied via output connector 1409 to output tube 1406 for
delivery to a user. The embodiment of FIG. 14 does not have the
return flow tube comparable to element 103 of FIG. 1.
[0157] Also, the massive base 1401 has two pairs of upwardly
extending walls whereas in the embodiment of FIG. 1 the massive
base 101 had only the single pair of upwardly extending walls 117
and 118. The single pair of walls in FIG. 1 performed the function
of being a zero motion vibrational node as well as a mounting for
connectors 107 through 110. On FIG. 14, the inner pair of walls
1417 and 1418 function as a zero motion vibrational node for the
ends of the active portion of flow tube 102. The outer pair of
upwardly extending walls 1443 and 1444 mount connectors 1408 on the
left and 1409 on the right.
[0158] When in use, process material is received from tube 1404
connected to connector 1408. The inlet of flow tube 1402 is also
connected to connector 1408. Flow tube 1402 extends the process
material flow to the right through the two pairs of sidewalls to
output connector 1409 to which is connected the output tube
1406.
[0159] The part numbers on FIG. 14 not specifically mentioned
immediately above are analogous to and perform the functions
identical to their corresponding elements on the previous FIGS.
including FIG. 1.
[0160] Description of FIG. 15
[0161] FIG. 15 discloses an alternative embodiment 1500 which is
similar in most respects to the embodiment of FIG. 1. The primary
difference is that in the embodiment of 1500, the rear flow tube
1503 is not dormant as is return tube 103 of the embodiment of FIG.
1. Instead, on FIG. 15, rear tube 1503 is vibrated by its driver DA
with the resulting Coriolis deflections of this vibrating tube with
material flow being detected by its pickoffs LP0A and RP0A. Their
output signals are transmitted over paths 1542 and 1544 to meter
electronics 1521 which receives these signals as well as signals
from pickoffs LP0 and RP0 of flow tube 1502 to generate material
flow information.
[0162] The process material flows to right on FIG. 15 through flow
tube 1502, through tube 1500 and flows to the left through flow
tube 1503. This phase reversal of mated pickoffs can be compensated
by reversing the connections to pickoffs. LP0A and RP0A so that the
Coriolis signals from all pickoffs received by meter electronics
1521 are additive to enhance meter sensitivity.
[0163] The parts shown on FIG. 15 not specifically mentioned above
are identical in function to their corresponding elements on FIG.
15.
[0164] Description of FIG. 16
[0165] FIG. 16 discloses an alternative embodiment 1600 that is
similar to the embodiment of FIG. 14. It has a base 1601, front
surface 1616, side walls 1644 and 1641 and front wall surfaces
1644. The differences are that upwardly extending inner
[0166] mounting posts 1617 and 1618 replace walls 1417 and 1418 of
FIG. 14. Also upwardly extending outer mounting posts 1643 and 1645
replace walls 1443 and 1445 of FIG. 14. Outer posts 1643 and 1645
prevent flow tube 1602 from pivoting about post 1617 and 1618 as an
axis. Connectors 1608 and 1609 are optional and if desired flow
tube 1602 may extend outwardly through posts 1643 and 1645 and
replace inlet tube 1604 and outlet tube 1402. The extended flow
tube may be connected downstream and upstream by a user to the
user's equipment. Posts 1443 and 1445 serve as a mounting for
connector 1608 and 1609 when provided.
[0167] It is to be expressly understood that the claimed invention
is not to be limited to the description of the preferred embodiment
but encompasses other modifications and alterations within the
scope and spirit of the inventive concept. For example, the
flowmeter embodiments shown herein may be operated in an upside
down orientation it is desired to have the driver D positioned on
top of a vibrating flow tube to allow the driver heat to move
upward away from the flow tube. This can better isolate the flow
tube from thermal stress that might degrade the accuracy or the
output data of the flowmeter. Also, the Coriolis flowmeter herein
disclosed has applications other than those herein disclosed. For
example the disclosed Coriolis flowmeter may be used in
applications in which the flowing process material is corrosive,
such as nitric acid, and incompatible for use with flow meters
having a metal wetted flow path.
* * * * *